| 摘要 |
PURPOSE:To reduce surface roughness of polished surfaces and improve accuracy in precise measurement and precise working of a large-sized sintered compact having a complicated shape by specifying the amount of fine granular alumina in sintering a cast formed compact of a clay-containing alumina body. CONSTITUTION:Alumina grains having <=1mu average grain diameter in an amount of >=20% based on the total amount of the alumina are contained in an alumina body containing 5-30% clay and the resultant body is cast formed and further burned in the atmosphere. Thereby, the pore diameter in the body is reduced to afford an alumina-based sintered compact having <=0.1mu surface roughness (center line average height) (Ra) of polished surfaces. Furthermore, if alumina grains having >1.0mu average grain diameter are used, sufficient effects on reduction in the pore diameter of the sintered compact are not observed. |
